Ingest data from NATS JetStream

You can ingest data from NATS JetStream into RisingWave by using the NATS source connector in RisingWave.

NATS is an open-source messaging system for cloud-native applications. It provides a lightweight publish-subscribe architecture for high-performance messaging.

NATS JetStream is a streaming data platform built on top of NATS. It enables real-time and historical access to streams of data via durable subscriptions and consumer groups.

Beta Feature

The NATS source connector in RisingWave is currently in Beta. Please contact us if you encounter any issues or have feedback.

Prerequisites

Before ingesting data from NATS JetStream into RisingWave, please ensure the following:

• The NATS JetStream server is running and accessible from your RisingWave cluster.
• If authentication is required for the NATS JetStream server, make sure you have the client username and password. The client user must have the subscribe permission for the subject.
• Create the NATS subject from which you want to ingest data.
• Ensure that your RisingWave cluster is running.

Ingest data into RisingWave

When creating a source, you can choose to persist the data from the source in RisingWave by using CREATE TABLE instead of CREATE SOURCE and specifying the connection settings and data format.

Syntax

CREATE { TABLE | SOURCE} [ IF NOT EXISTS ] source_name 
[ schema_definition ]
WITH (
   connector='nats',
   server_url='<your nats server>:<port>', [ <another_server_url_if_available>, ...]
   subject='<subject>[,<another_subject...]',
   stream='stream_name',

-- optional parameters
   connect_mode=<connect_mode>
   username='<your user name>',
   password='<your password>'
   jwt=`<your jwt>`,
   nkey=`<your nkey>`

-- delivery parameters
   scan.startup.mode=`startup_mode`
   scan.startup.timestamp.millis='xxxxx',
)
FORMAT PLAIN ENCODE data_encode;

schema_definition:

(
   column_name data_type [ PRIMARY KEY ], ...
   [ PRIMARY KEY ( column_name, ... ) ]
)

note

RisingWave performs primary key constraint checks on tables with connector settings but not on regular sources. If you need the checks to be performed, please create a table with connector settings.

For a table with primary key constraints, if a new data record with an existing key comes in, the new record will overwrite the existing record.

note

According to the NATS documentation, stream names must adhere to subject naming rules as well as being friendly to the file system. Here are the recommended guidelines for stream names:

• Use alphanumeric values.
• Avoid spaces, tabs, periods (.), greater than (>) or asterisks (*).
• Do not include path separators (forward slash or backward slash).
• Keep the name length limited to 32 characters as the JetStream storage directories include the account, stream name, and consumer name.
• Avoid using reserved file names like NUL or LPT1.
• Be cautious of case sensitivity in file systems. To prevent collisions, ensure that stream or account names do not clash due to case differences. For example, Foo and foo would collide on Windows or macOS systems.

Parameters

Field	Notes
server_url	Required. URLs of the NATS JetStream server, in the format of address:port. If multiple addresses are specified, use commas to separate them.
subject	Required. NATS subject that you want to ingest data from. To specify more than one subjects, use a comma.
stream	Required. NATS stream that you want to ingest data from.
connect_mode	Required. Authentication mode for the connection. Allowed values: plain: No authentication. user_and_password: Use user name and password for authentication. For this option, username and password must be specified. credential: Use JSON Web Token (JWT) and NKeys for authentication. For this option, jwt and nkey must be specified.
jwt and nkey	JWT and NKEY for authentication. For details, see JWT and NKeys.
username and password	Conditional. The client user name and pasword. Required when connect_mode is user_and_password.
scan.startup.mode	Optional. The offset mode that RisingWave will use to consume data. The supported modes are: earliest: Consume data from the earliest offset. latest: Consume data from the latest offset. timestamp_millis: Consume data from a particular UNIX timestamp, which is specified via scan.startup.timestamp.millis. If not specified, the default value earliest will be used.
scan.startup.timestamp.millis	Conditional. Required when scan.startup.mode is timestamp_millis. RisingWave will start to consume data from
data_encode	Supported encodes: JSON, PROTOBUF, BYTES.

Examples

The following SQL query creates a table that ingests data from a NATS JetStream source.

CREATE TABLE live_stream_metrics
WITH
  (
    connector = 'nats',
    server_url = 'nats-server:4222',
    subject = 'live_stream_metrics',
    stream = 'risingwave',
    connect_mode = 'plain'
  ) FORMAT PLAIN ENCODE PROTOBUF (
    message = 'livestream.schema.LiveStreamMetrics',
    schema.location = 'http://file_server:8080/schema'
  );